Circuit breaker



Au .6,1929. w, UL 1,723,ssa

' CIRCUIT BREAKER Filed Aug. 4, 1921 Fig.1.

R, Y I V V I! 40 HEMP k Fig. 5. E Inventor: Albert WQHUII,

1 /r fi /Vm/ MAG/V5776 HELD i His Attorney- Patented Aug. 6, 1 929.

' UNITED STATES PATENT OFFECE.

ALBERT W. HULL, OF SCHENECTADY, NEW YORK, ASSIGNOR T GENERAL ELECTRICCOMPANY, A CORPORATION OF N EW YORK.

cmcui'r BREAKER.

Application filed August 4, 1921. Serial No. 489,823.

My present invention comprise a circuit breaker or switch which isparticularly adapted for the interruption of high voltage urrents. It isthe object of my invention to provide anapparatus for safelyinterrupting powerful electrical currents with a minimum of disturbanceto the transmission line.

In accordance with my invention I have provided an apparatus whereby thecurrent is reduced to zero by a field of force operating on an'electrondischarge in a vacuum, thereby preventing arcing, with no accompanyingsurges or other disturbances.

everal embodiments of my invention have been shown in the accompanyingdrawing in which Figs. 1 and 2 illustrate respectively by diagram analternating current system and a direct current system equipped with acircuit breaking apparatus embodying my invention; Fig. 3 is a graph ofelectrical characteristics involved in the operation of my newapparatus; and Fig. 4 illustrates diagran'imatically a system in whichthe circuit is opened automatically when an unusual rise of currentoccurs.

Fig. 2 represents one of the simplest embodiments of my invention;namely, a direct current system comprising a generator connected tomains 5 and 6, an electron discharge tube 7 being adapted to beintercalated in the conductor 6 by opening a switch 7. The electrondevice 7 comprises a cylindrical anode 8 surrounding a filamentarylinear cathode 9 and an enclosing evacuated envelo e 10. The cathode isconnected by a CODClTlCtOl 11 to a source of en ergy, represented by abattery 12, whereby the cathode may be rendered incandescent.Surrounding the envelope is a helical magnetic winding 18 connected to asource of.

current, such, for example, as a battery 1 1 by a circuit 15 containinga switch 16.

The device 7 is known as a magnetron and is hereinafter in thisspecification and claims referred to by this term. The magnetron in ageneral aspect is described and tainied in my Patents No. 1,523,77 6issued Januar 20, 1925, and No. 1,523,778 also issued anuary 20, 1925and in the Trans actions of the American Institute of ElectricalEngineers, for September, 1921. In the preferred embodiment of amagnetron illustrated in the drawings, the cathode is substantiallyequidistant from the anode at all points along its length. Otherconstructions affording circular symmetry of the electrodes may be used.The evacuation of the devi e preferably is so complete that positiveionization of residual gas is negligible although this is not essential.

Assuming the double pole switch 17 in the mains 5 and 6 closed and theswitch 7 closed, the following sequence of steps may be carried out whenit is desired to open the circuit which may be of high voltage. Theswitch 18 in the cathode heating circuit 11 is closed thereby bringingthe cathode of the magnetron to a state of incandescence at which itemits electrons. The switch 7 in parallel with the magnetron isthereupon opened, causing the current in the conductors 5 and 6 to becarried entirely by the magnetron. The opening of this switch 7 isunaccompanied by sparking or disturbances due to the relatively lowvoltage drop in the magnetron. The switch 16 in circuit with the winding13 is next closed, generating an electromagnetic field substantiallyparallel to the cathode. Theeifect of this field is to deflect theelectrons carrying the current in the space between the electrodescausing the electrons to assume circular paths about the cathode andpreventing them from reaching the anode. 4

Fig. 3 shows the relation between-current in the device and the magneticfield, the current values being plotted as ordinates and the values ofthe magnetic field being plotted as abscissae. It will be noted from thecurve 20 that up to a value it of the magnetic field, the current issubstantially unaflected but a further increase of the mag netic fieldcauses an abrupt decrease of current so that at a value 70 the currenthas fallen to substantially zero. The value oi the magnetic fieldgenerated by the winding 13 is chosen to cause the current to fall toZero orsubstantially so. v

A double pole switch 17, which may be mechanically operated, finally maybe.

ened disconnectin the mains 5 and 6 ermanently. The switches 16 and 18there u on ma be disconnected if desired takin P y a 3 they electrondischarge tube out of service. The action of the magnetic field inreducing the current is unaccompanied bysurges and other disturbances inthe circuit and of I course'being in a vacuumis free from theconditions.

danger which is present when arcing takes place in the open air.

Fig. 1 shows two magnetrons 21, 22, connected to an alternating currentcircuit 23,

24, these devices being oppositely connected in series with thealternating current circuit and'being adapted to carry current derivedfrom the secondary winding of a transformer 25. The anode of the tube 21and the. cathode ofthe tube 22 are both connected to the main 23, thecathode of the tube 21 and the anode of tube 22 being connected to theconductor 26, which isa continuation of the conductor 23. When theswitch 27 isopened current of one polarity will pass through the tube 21and current-0f opposite polarity through the tube 22. The cathodes oftubes 21, 22 are respectively heated by batteries 28, 29, or othersuitable sourcespf current. When it is desired to disconnect thealternating current circuit.

from the load 30 the switch 27 is opened, inserting the magnetrons incircuit.

switch 31 then is closed energizing the ma gnetic windings 32, 33, andthereby setting up in the current carrying path'of each tube a field offorce which deflects the electrons, as already explained, and reducesthe current to zero or substantially so. The mechanically operatedswitch 34 in the conductor 26' may thereupon be opened. The magnetronshaving performed their function and being cut out of circuit may bedeenergized if desired.

Fig. 4 shows a magnetron adapted to be connected automatically. with themains 36, 37 which carry current froma direct current generator 38. Thecathode 9 is energized by a suitable source of. current such as abattery 39 in circuit with conductors- 40, 41, containing a mechanicallyoperated contact 42. This contact is operated by a magnet 43, which isone of a group of sequentially operated magnets connected in series withthe main 36. The electric and magnetic characteristics of the magnet 43and its armature are so chosen that the contact 42 is open during normalcurrent When an unusual rise of current occurs in the mains 36, .37, themagnet 42 pulls up its armature closing the contact 42, thereby heatingto incandescence the cathode 9 of the magnetron. The magnet 45 is timedto next attract its armature 46 and open normally closed contact 47,thereby causing current to flow through themagnetron instead of throughthe conductors 48, 49. The magnet 50 will next attract its armature,closing thecontact 51 ina circuit 52, energizing the magnetizing winding13, and cutting oil'current in the magnetron 35. The magnet 53 willoperate next by opening the contacts 54 in the circuit 55, 56. -Theswitch 57 may finally be opened manually or otherwise, therebypermanently opening the current carrying mains.

It is is desired to open the circuit very quickly, as in case'of a shortcircuit, the cathode of the magnetron may be maintained continually atincandescence by permanently closing the contact 42, or means may beused for auxiliary heating depend ing on the rate of change of currentin the line 36, 37. I have indicated'as illustrative netron cathode atransformer 60 having a primary connected in the line 37 and containinga condenser 61 in thesecondary to of auxiliary heating means for themag-,

prevent discharge of the battery. A choke coil 62in the battery circuitmay also be provided topreve'nt discharge of the transformer currentthrough the battery, circuit.

When in the accompanying claims I have inserting the same into saidcircuit and en- Y erglzing the field winding of said magnetron to astrength sufficient to interrupt said current, and means for thereupondisconnecting said magnetron.

. 2. A switching apparatus comprising a.

circuit to be opened and closed, a magnetron, connections for includingsaid magnetron in said circuit and a plurality of sequentially operatedcontactors, constituted first,

.by a contactor having a. contact included in the cathode heatingcircuit of said magnetron? second, a contactor having a contact inmultiple with, said magnetron; third, a contactor having a contactin themagnetizing circuit of said magnetron and fourth,a contactor in serieswith said magnetron, said contactors being timed to operate in the ordernamed.

3. A current control apparatus including a normally energized circuit tobe opened and closed, a normally deenergized magnetron, means forinserting and withdrawingsaid magnetron. from said circuit and meanscontrolled in accordance with an electrical condition of said circu1tfor creating 1n said magnetron a magnetlc field vof sufficient value toreduce the current the cathode and magnetic winding of said magnetron,and a second contactor in series with the electrodes of said magnetron.

5. The combination of-an electrical power circuit, a switch connected insaid circuit, an electron discharge device including an anode connectedto one terminal of said switch and a cathode connected to the otherterminal of said switch, means for energizing said device, means foropening said switch, and means for dcenergizing said device, said meansbeing responsive to a predetermined electrical condition of saidcircuit.

6. The combination of an electrical power circuit, a switch connected insaid circuit, an electron discharge device including an anode connectedto one terminal of said switch and a cathode connected to the otherterminal of said switch, means for energizing said device, means foropening said switch, means for deenergizing said device, and means foropening said circuit, said means being responsive in sequence in theorder named, to a predetermined electrical condition of said circuit.

In witness whereof, I have hereunto set my hand this 3rd day of August,1921.

v ALBERT W. HULL.

